Translating device



Aug. 20-, 1929. s, v, PERRY 1,725,157

TRANSLATING DEVICE Filed June 29, 1928 INVENTOR 7 ATT'oRNEY Patented Aug. 20, 1929.

UNITED STATES SYDNEY V. PERRY, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTBIC & MANUFACTURING VANIA.

COMPANY, A CORPORATION OF PENNSYL- TRANSLATING DEVICE.

Application filed June 29,

My invention relates to translating devices and, more particularly, to devices of the type known as loud speakers for translating electrical current variations into sound waves.

At the present time, loud speakers may be divided into three main classes, in so far as their drivers or actuating portions are concerned; namely, those individually having a movable armature, those individually provided with a diaphragm of magnetic material which is directly acted upon by a magnetic element, and those in which the currents representative of sounds are caused to flow in a small coil suspended in an air gap in a magnetic circuit.

In a loud-speaker motor of the first type, exemplified by the patent to Egerton No. 1,365,898, wherein the movable armature is suspended from a flexible torsion-spring, a considerable amount of diiiiculty has heretofore been experienced in preventing the actuating coils from loosening and, consequently, interfering with the vibration of the armature. One way of preventing such in terference is disclosed in the Egerton patent, wherein a plurality of spacing pins are shown as extending from the inner surfaces of the pole-pieces between which the actuating coils are disposed, it being the patentees intention that these pins should function to maintain the coils sufficiently separated to prevent them from coming in contact with the armaturemounting spring. The spacing pins, however, are not effective in keeping the coils in position, since they make contact only near the peripheries thereof. This is especially true where the diameter of the coils is large, as compared with their axial length.

In addition, the provision of the spacing pins entails additional steps in the manufacture of the device and increases the cost of production.

It is, accordingly, an object of my invention to provide improved means for maintaining the actuating coils of a loud-speaker driver properly spaced apart.

Another object of my invention is to provide improved means whereby the actuating coils of a loud-speaker driver are prevented from coming into contact with the element from which the moving member of the motor is suspended.

Another, and more specific object of my in vention, is to provide means for firmly holding the coils of a loud-speaker driver in posi- 1928. Serial No. 289,187.

tion relative to the magnetic pole-pieces associated therewith.

In accordance with my invention, a loud speaker of the type comprising a fixed magnet having removable pole-pieces and nonmagnetic pole-piece-adjustin g elements associated therewith is further provided with a peculiarly shaped coil-spacing element, also of non-magnetic material, which element is clamped to the pole-piece-adjusting elements by the same means that affix the armature suspension spring thereto. The spacing element has a central opening therethrough which is wider than the suspension spring, and the edges of the element are bent downward to provide bearing surfaces against which one of the actuating coils abuts. The spacing element is slightly concave longitudinally thereof, whereby the edges that are bent downward are somewhat offset from the plane of the central opening to provide hearing surfaces for the other actuating coil.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with further objects and advantage thereof, will best be understood by reference to the following description of a specific em bodiment, taken with the accompanying drawing, in which:

Figure 1 is a view, in perspective, showing a preferred embodiment of my invention as applied to a loud-speaker driver of the type disclosed in the Egerton patent hereinbefore referred to, and

Fig. 2 is a fragmentary view, partly in elevation and partly in cross-section, illustrating the relation between my improved coilspacing device and the actuating coils; and

Fig. 3 is an exploded view of the apparatus shown in Fig. 1,

The loud-speaker motor illustrated in the drawings comprises a permanent magnet 1, to opposite ends of which removable pole pieces 2 are respectively secured. Each pole piece is provided with a pair of pole extensions 3 which are separated sufficiently to receive a pair of actuating coils 4 between them.

Each pole-piece 2 is held firmly against the end of the permanent magnet by a bolt 5, which extends through an opening 6 in the pole-piece and an opening 7 in the end of the permanent magnet. The diameters of the openings in the pole-pieces and those in the magnet are slightly larger than those of the bolts 5, to permit the pole pieces to be adjusted, in a manner hereinafter described.

A plurality of L-shape spacingmembers 8, of non-magnetic material, are provided for the purpose of maintaining the pole-extensions 3 properly spaced apart to receive an armature 10 between them. Each of the members 8 is secured to its companion polepiece by a screw 11 which extends through an opening 12 in the pole piece and engages a threaded opening 13 in the member.

The openings 12 may be countersunk to receive the head of the screw, and both the opening and the countersinking are larger than the shank ot the screw and its'head, respectively, thus permitting the members to be adjusted both longitudinally and transversely, relative to their companion pole pieces. The members 8 are also provided with grooves 14 designed to receive screws 15, and threaded recesses 16 are provided in the respective opposing pole pieces. The grooves 14 are slightly wider and deeper than the threaded screws 15, to provide for both vertical and transverse adjustment of the spacing members.

The armature 10 is mounted on a resilient torsion-member 20, and extends through the central openings in the coils 4. A small opening 21 is provided in one end of the ar mature 10, into which is brazed or soldered one end of a connecting wire 22. The other end of the connecting wire is soldered or otherwise affixed to a coupling element 23. The coupling element, which has a flexible portion 24, is atiixed to one of the pole-pieces by a screw 25, which engages athreaded opening 26 in the pole piece. The end oi the element opposite to the flexible portion 24a is provided with an opening in which a small screw 27 may be brazed or soldered to a diaphragm (not shown).

Each end of the member is provided with an elongated opening 28, through which extend mounting screws 30 to engage threaded openings 31 provided in the spacing members 8. A coil-spacing element 32 of thin, somewhat resilient, non-magnetic material, such as sheet brass, is also disposed between the spacing elements 8 andis held in position by the screws 30 which hold the torsion member 20. The spacing member is roughly rectangular in shape, having a central opening 33 which is slightly wider than the torsion member 20.

The spacing member, which is slightly concave longitudinally, is provided with turneddown flanges 34 which, when the member is in position, serve as abutments for one of the coils 4. The other coil bears against the edges of the spacing'member opposite to theflanges 34 and, since the member is somewhat trough shaped, both coils are thus held firmly out-sideof the space in which the torsion member vibrates.

Since the opening in the coil spacer is wider than the torsion member, there is no possibility that they will come in contact during the operation of the device and cause buzzing or unpleasant sounds.

My improved spacing device is particularly advantageous when the actuating coils are so large in diameter as compared with their thickness that they bend easily when subjected to atmospheric changes. Unless the insulating washers at eacn side of the coils are made unduly thick, spacing elements, such. as those shown in the Egerton patent, are ineffective to prevent the centers of the coils from warping into contact with the torsion memher. The use of thick washers is not desirable, however, since the space available for the winding is greatly reduced thereby, and, as a consequence, the quality of reproduction obtainable from the loud speaker is impaired. On the other hand, my improved device entirely obviates the necessity of making use of thick insulating washers to support the coils and, by supporting them along chords thereof instead of at their peripheries only, positively prevents them from coming into contact with the torsion-member, irrespective of atmospheric conditions.

Although I have illustrated my invention as being particularly applicable to a loudspeaker motor of the type disclosed in the Egerton patent No. 1,365,898, it will readily be apparent to persons skilled in the art that my invention is equally applicable to many other translating devices, either telephone transmitters or loud speakers, of the type wherein an armature is resiliently mounted adjacent to a coil which has a tendency to move and, consequently, make contact with the resilient mountingelements.

The scope of my invention, therefore, is not to be limited except in so far as is necessitated by the prior art, or by the spirit of the appended claims.

I claim as my invention:

1. In telephonic apparatus, a magnetic circuit comprising a pair of pole pieces, an armature disposed between said pole pieces, resilient suspending means for said armature,

mounting means for said suspending means,

an actuating coil for said armature disposed adjacent thereto, and means carried by said mounting means for preventing said coil from coming into contact with said resilient suspending means.

2. In telephonic apparatus, a magnetic circuit comprising-a pair of pole pieces disposed in overlapping spaced relation to each other, an armature, a torsional mounting for said armature. supporting means for said torsion a1 mounting, a pair of actuating coils surrounding said armature and disposed on opposite sides of said torsional mounting, and means carried by said supporting means for preventing said coils from coming into contact with said torsional mounting.

3. In telephonic apparatus, a magnetic circuit comprising a pair of pole pieces disposed in overlapping spaced relation to each other, an armature, a torsional mounting for said armature, supporting means for said torsional mounting, a pair of actuating coils surrounding said armature and disposed on opposite sides of said torsional mounting, and a spacing element having a central opening, said spacing element having offset portions and being so mounted on said supporting means that the said offset portions serve to space said coils apart and prevent them from coming into contact with said torsional mounting.

4. In telephonic apparatus, a magnet, a

pair of pole pieces carried by said magnet and disposed in overlapping spaced relation, securing members extending between and afiixed to each of said pole pieces, a movable armature, a torsional mounting for said armature secured to said members, a pair of stationary coils surrounding said armature and located on opposite sides thereof, and an elongated coil-spacing member afiixed to said securing members, said spacing member hav ing portions thereof OiISQt to provide abutments for the said coils, whereby the coils are prevented from coming into contact with said torsional mounting.

In testimony whereof, I have hereunto subscribed my name this 25th day of June 1928.

SYDNEY V. PERRY. 

